An amateur radio net, or simply ham net, is an “on-the-air” gathering of amateur radio operators. Most nets convene on a regular schedule and specific frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

, and are organized for a particular purpose, such as relaying messages, discussing a common topic of interest, in severe weather (for example, during a Skywarn

Skywarn

SKYWARN is a program of the United States' National Weather Service . Its mission is to collect reports of localized severe weather. These reports are used to aid forecasters in issuing and verifying severe weather watches and warnings and to improve the forecasting and warning processes and the...

 activation), emergencies, or simply as a regular gathering of friends for conversation.

Net operation

Nets operate more or less formally depending on their purpose and organization. Groups of nets may organize and operate in collaboration for a common purpose, such as to pass along emergency messages in time of disaster. One such system of nets is the National Traffic System

National Traffic System

The National Traffic System is an organized network of amateur radio operators sponsored by the American Radio Relay League for the purpose of relaying messages throughout the US and Canada....

 (NTS), organized and operated by members of the American Radio Relay League

American Radio Relay League

The American Radio Relay League is the largest membership association of amateur radio enthusiasts in the USA. ARRL is a non-profit organization, and was founded in May 1914 by Hiram Percy Maxim of Hartford, Connecticut...

 (ARRL) to handle routine and emergency messages on a nationwide and local basis.

Formal operation

A formal, or directed net has a single net control station (NCS) that manages its operation for a given session. The NCS operator calls the net to order at its designated start time, periodically calls for participants to join, listens for them to answer (or check in ) keeps track of the roster of stations for that particular net session, and generally orchestrates the operation of the net.

A different station might be designated NCS for each net session. Overall operation and scheduling of NCS assignments and net sessions is managed by the net manager .

When a net covers a large geographic area, such as a continent or even the world, it becomes impractical for a single NCS to control. To cover a large scale area a net must operate on a frequency where signals can propagate

Radio propagation

Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...

 long distances. Ironically, the same ability for long distance propagation leads to a situation where stations that are too close in proximity can not hear each other. In this case two or more NCSs spaced geographically from one another can effectively collaborate to maintain contact with all possible participants.

Informal operation

An informal net may also have a net control station, but lack some or all of the formalities and protocols other than those used in non-net on-the-air operation. Or, it could begin at the designated time and frequency in an ad hoc fashion by whoever arrives first. Club nets, such as ones for discussing equipment or other topics, use a NCS simply to control the order in which participants transmit their comments to the group in round-robin

Round-robin

The term round-robin was originally used to describe a document signed by multiple parties in a circle to make it more difficult to determine the order in which it was signed, thus preventing a ringleader from being identified...

 style.

Traffic

Traffic nets operate primarily to relay written messages. For decades, amateur radio operators passed both routine and emergency messages on behalf of others as part of its public-service mission.

Today, with inexpensive communication capability available to anyone, routine message handling has dwindled and is largely used for training purposes. During emergencies (such as natural disasters) – especially when normal communications channels are disabled or compromised – traffic nets (utilizing emergency-powered stations) are used to pass information into and out of affected areas.

DX

DX

DXing

DXing is the hobby of tuning in and identifying distant radio or television signals, or making two way radio contact with distant stations in amateur radio, citizens' band radio or other two way radio communications. Many DXers also attempt to receive written verifications of reception from the...

 nets are organized to help amateur radio operators make contact with stations in distant locations or regions where amateur radio operators are scarce. By checking into a DX net, a ham

Etymology of ham radio

Ham is an informal term for an amateur radio operator, and, by extension, "ham radio" refers to amateur radio in general. This use of the word first appeared in the United States during the opening decade of the 20th century—for example, in 1909 Robert A...

 could have a chance to contact another station he or she might otherwise not be likely to hear by randomly tuning across the amateur bands

Amateur radio frequency allocations

Amateur radio frequency allocation is done by national telecommunications authorities. Globally, the International Telecommunication Union oversees how much radio spectrum is set aside for amateur radio transmissions...

.

Club or Topic

Amateur radio clubs often organize nets to foster communication between members on a regular basis. These can be clubs based on geographic location or clubs formed around a special interest.

Special interest clubs or non-club groups often organize nets to enable discussions on a particular topic. A wide variety of such nets are in operation. One such example is nets that meet to discuss vintage

Vintage amateur radio

Vintage amateur radio is a subset of the amateur radio hobby, considered a form of nostalgia much like antique car collecting, where enthusiasts collect, restore, preserve, build, and operate amateur radio equipment from bygone years, most notably those using vacuum tube technology.Popular modes of...

or antique radio equipment. Another example is nets for using and discussing the AM mode of voice transmission.